.middle > div {
    border: 1px solid red;
}

.middle > div > div {
    padding: 10px;
}

.online {
    border-top: 1px solid red;

}

.online > div:nth-child(1) {
    text-align: center;
}

/*让div左右居中*/
.online > div:nth-child(1) > div:nth-child(1) {
    display: flex;
    justify-content: center;
}

/*让div上下居中*/
.online > div:nth-child(1) > div:nth-child(1) > div {
    display: flex;
    align-items: center;
}

cc {
    color: orange;
    font-size: 30px;
    /*line-height: 50px;*/
}

bb {
    color: gray;
    font-size: 20px;
    /*line-height:50px;*/
}

/*-------------------------------*/
.online > div:nth-child(2) {
    /*border: 1px solid red;*/
    display: flex;
    justify-content: center;
}

.online > div:nth-child(2) > div {
    width: 600px;
    /*border: 1px solid blue;*/
    margin: 50px 0;
}

form > div > div {
    line-height: 30px;
}

/*.content > div > div:nth-child(2) {*/
/*    height: 30px;*/
/*    background-color: rgb(238, 238, 238);*/
/*    border: 1px dashed gray;*/
/*    padding: 0 10px;*/

/*}*/

/*.content > div:nth-child(3) > div:nth-child(2) {*/
/*    height: 100px;*/
/*    line-height: 20px;*/
/*    font-size: 15px;*/
/*}*/
input[type=text], textarea {
    width: 600px;
    background-color: rgb(238, 238, 238);
    border: 1px dashed gray;
    line-height: 30px;
    padding: 0 10px;
}

textarea {
    line-height: 20px;
    height: 100px;
}

.online > div:nth-child(2) > div > div:nth-child(2) {
    display: flex;
    justify-content: center;
    margin: 30px;
}

input[type=submit] {
    padding: 10px 50px;
    background-color: orange;
    color: white;
    border: none;
}

input[type=submit]:hover {
    background-color: rgb(230, 145, 55);
}